699 



existence of a maximum-limil for the tirst range of coagulation, as 

 fixed by Chossley ; from the above il is perfectly clear that this 

 criticism is absolutely without ground, and that the maximum-limit, 

 described by Parkin and Crossi.ey does really exist; but only with 

 mixtures with a percentage of latex below a certain limit. 



G. S. Whithby ') was the first one who emphatically pointed out 

 the existence of the second range of coagulation above the second 

 liquid range and described a few complete series liquid coagulated — 

 liquid — coagulated. Whitby for these phenomena assumed the explana- 

 tion that small quantities of acid have an activating influence on an 

 enzym, which is found in latex, coagulase, which, at a small acidity, 

 would cause the coagulation, but at a higher acidity would become 

 inactive; the second range of coagulation then would be a direct 

 precipitation of protein by larger quantities of acid. 



We shall now compare the observations of the last two investi- 

 gators with our own. 



1. H;nlrochloric dcid. In Fig. 6 the limits have been taken from 

 Fig. 2, and therein have been drawn the observations made by 

 Eaton and Whitby. 



Starting from undiluted latex Eaton found with lO'/o afid (I'ne 1 

 in tig. 6) a continual series of coagulations, but with 1 7. acid 



Fig. 6. 



(line 2) he got into the liquid range. Two series with 1 : 2 diluted 



1) Zeitschr. KoU. (Jhem. 12 (1913), 156, India Rubber Journal (London) 45 

 1913), 945; further Agric. Bull, of the Dept. of Agr. F.M.S. (Kuala Lumpur) 6 

 (1918), 381. 



46* 



